GIS APPLICATIONS IN EARTHQUAKES

ASSESSMENT

Prepared by:

Abdullah A. Al-Shuhail

I.D. # 959240

Prepared for:

CRP 514: GIS

Term 021

(9th offer)

Instructor:

Dr. Baqer Al-Ramadan

January 21, 2002

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OUTLINE

ABSTRACT

1. INTRODUCTION

2. BACKGROUND: EARTHQUAKES

2.1 Definition

2.2 Measurements

2.2.1 Richter’s Scale

2.2.2 Modified Mercalli Scale

2.3 Effects

3. GIS APPLICATIONS IN EARTHQUAKE ASSESSMENT

3.1 Why GIS?

3.2 How GIS is Used?

3.3 Case Studies:

3.3.1 1989 Newcastle Earthquake, Australia

3.3.2 Island of Cyprus

3.3.3 Mapping the Big One, CA, USA

4. CONCLUSION/RECOMMENDATIONS

REFERENCES

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ABSTRACT

Earthquakes are amongst the worst natural disasters on Earth. This

paper deals, briefly, with earthquake as a natural hazard and how to minimize

their effects using Geographic Information System. The paper starts with

background of earthquakes, definition and effects. Then, some of the GIS

applications in earthquake hazards are discussed and case studies are given

from different countries and the paper closes with a conclusion.

1. INTRODUCTION

Earthquakes are one of the most devastating geohazards. Over 30,000

earthquakes are felt worldwide annually, 75 among which are considered

significant earthquakes. Depending on number of factors including the

magnitude, duration, the intensity and the population density, a significant

earthquake may cause death to tens of thousands; and sometimes more as in

1976 Tangshan earthquake in China (about 240,000 deaths), and losses in

billion of dollars, as in Kobe earthquake, Japan, January 1995 (losses

estimated to be more than $100 billion) (Tarbuck).

GIS, Geographic Information System, is a computer-based system that

is used to store and manipulate geographic information. This technique, which

associates the attributes with its geographic location, has developed so

rapidly over the past two decades that is has become an essential tool in

geosciences. In geophysics, the GIS technique has found a wide range of

applications since it is very important to represent the geophysical data in their

geographic location.

The main objective of this paper is to briefly discuss earthquake as a

natural hazard and how to minimize their effects using Geographic Information

System. This paper starts with background of earthquakes, definition and

effects. Then, the paper describes, briefly, why and how GIS is used in the

assessment of earthquakes: before, during and after an event. After that,

some of the GIS applications in earthquake hazards are mentioned through

three different case studies from three different continents before closing with

a conclusion.

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2. BACKGROUND: EARTHQUAKES

Before discussing the GIS applications in earthquakes assessment,

and in order to minimize the impact of earthquakes, once should know the

some of the basic information about earthquakes that include: definition,

measurements and effects.

2.1 Definition

An earthquake is a sudden vibration of the earth produced by a rapid

release of accumulated strain energy that radiates in all direction from its

source, the focus, in the form of seismic waves (Figure 1).

An earthquake may be accompanied with foreshock and/or

aftershocks. A foreshock is a small earthquake that often precedes the main

shock by days, or some cases, by as much as several years. An aftershock is

a small earthquake that follows the main shock. Aftershocks can cause a

considerable damage to the weakened structures (Tarbuck).

Figure 1: Illustration of Earthquake. The Epicenter is the surface location directly above the focus and the distance between the epicenter and the focus is called the Focal depth (Tarbuck).

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2.2 Measurements

There are two main methods by which earthquakes can be measured:

1) Magnitude (Richter’s Scale) and 2) Intensity (Modified Mercalli Intensity

Scale).

2.2.1. Richter’s Scale (Open Scale, Table 1)

A magnitude scale that measures the energy released at the source of

the earthquake. The magnitude, also called local magnitude (ML), is

determined from measurements on seismographs (t and amplitude) and by

using the following formula (see Figure 2):

ML= log10 A/T + Q + C, A is the max. amplitude in m, T is period in

sec, Q (h) a function of depth and epicenter, C is a constant (Bolt).

2.2.2 Modified Mercalli Intensity Scale (Closed Scale, Table 1)

An intensity scale that consists of twelve grades and measures the

strength of shaking produced by the earthquake at a certain location

depending mainly on the damage caused to various types of structures.

There are other types of magnitude measures, such as, body-waves

magnitude (Mb, for seismic waves having period T = 1 sec.) and surface-

waves magnitude (Ms, T = 20 sec.). Also, there are other types of intensity

measures, e.g. Rossi scale and Forel scale. Table 1 shows the relation

between magnitude and the equivalent intensity (Bolt).

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Figure 2: Richter’s magnitude scale, called nomogram. There are three steps to determine the magnitude: 1) measuring the difference in arrival time between P and S waves and therefore the distance to the epicenter in km (using seismological tables), 2) measuring the maximum amplitude in mm, and 3) connect 1) and 2) through the magnitude scale by a straight line. In this nomogram, an earthquake at distance of 100 km and having maximum amplitude of 1 mm will result in magnitude of 3 according to Richter’s scale. Note that an increase in the magnitude by 1 unit will result in increase in the amplitude by a factor of 10 (Tarbuck & S:9).

Magnitude Intensity Description

1.0 - 3.0 Very Minor

I I. Not felt except by a very few under especially favorable conditions.

3.0 - 3.9 Minor

II - III II. Felt only by a few persons at rest, especially on upper floors of buildings.

III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.

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4.0 - 4.9 Light

IV - V IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.

V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.

5.0 - 5.9 Moderate

VI - VII VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures.

4.0 - 6.9 Strong

VIII - IX VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, and heavy furniture overturned.

IX. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.

7.0 and higher

Major, Great

X - XII X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.

XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly.

XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.

Table 1: Magnitude and equivalent intensity (S:9).

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2.3 Effects

The effects of any earthquake depend on a number of varying factors:

1) Intrinsic to the earthquake: its magnitude, type, location, duration and

depth, 2) Geologic conditions: where effects are felt, distance from the event,

path of the seismic waves, types of soil, water saturation of soil, and 3)

Societal conditions: reacting to the earthquake, quality of construction,

preparedness of populace, or time of day (e.g. rush hour) (S:9).

There are two classes of earthquake effects: Direct, and Secondary.

Direct effects are solely those related to the deformation of the ground near

the earthquake fault itself. Thus direct effects are limited to the area of the

exposed fault rupture, e.g. fissure and elastic rebounds (or fault

displacements. However, Most of the damage done by earthquakes is due to

their secondary effects, those not directly caused by fault movement, but

resulting instead from the propagation of seismic waves away from the fault

rupture. Secondary effects result from the very temporary passage of seismic

waves, but can occur over very large regions, causing wide-spread damage.

Such effects include: avalanches, ground settlement and the triggering of

aftershocks (S:9).

Below are brief explanations of some of the most common seismic

hazards (hazard associated with potential earthquakes in a particular area):

a) Ground Shaking: a rapid horizontal movement.

b) Liquefaction: in water-saturated soil; the transformation of stable soil into a

fluid that is often unable to support building or other structures (Figure 3)

(Tarbuck).

Figure: 3 Effect of liquefaction during 1999 Izmit earthquake, Turkey (S:1).

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c) Fire: during 1906 San Francisco earthquake, for example, the greatest

damage was caused by fires when electrical and gas lines were severed.

(Figure 4) (Tarbuck).

Figure 4: A raging fire at Turkey's largest oil refinery in the hard-hit Izmit, sparked by the devastating earthquake, was finally burning down three days later (S:6).

d) Flooding: a temporary condition of inundation of land adjacent to river

channel or along shoreline of lake, sea or ocean. Below are some of the

flooding events that are caused by earthquakes:

i. Tsunami (seismic sea waves): a rapidly moving ocean waves

generated by earthquake activity, which is capable of inflicting heavy

damage in coastal area (Figures 5 and 6). Tsunami can get as high as

30 meters (Tarbuck).

Figure 5: Schematic drawing of tsunami generated by displacement of the ocean floor (Tarbuck).

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Figure 6: Debris scattered by a tsunami that struck, Aonae, Japan, in July 1993 (Tarbuck).

ii. Floods caused from dam and levee failure caused by earth vibrations

(Tarbuck).

e) Seiches: rhythmic sloshing of water in lakes, reservoir and enclosed basins

(Tarbuck).

f) Landslides and ground subsidence: caused by shaking and lurching ground.

In 1964 Alaskan earthquake, for example, the greatest damage to structure

was from landslides and ground subsidence triggered by the vibrations

(Figure 7). The vibrations, also, caused the material to experience liquefaction

(Tarbuck).

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Figure 7: Turnagain Heights slide by the 1964 Alaskan earthquake. A. Cracks near the edge of the bluff caused by the vibration. B. Within seconds blocks of land began to slide toward the sea on a weak layer of clay. C. In less than five minutes, as much as 200 m of Turnagain Heights bluff area had been destroyed (Tarbuck).

3. GIS APPLICATIONS IN EQ ASSESSMENT

3.1 Why GIS?

GIS has provided a very efficient tool in the field of earthquake hazards

assessment. Prior to GIS, seismologist used the isoseismal maps (Figure 8),

earthquakes risk maps (Figure 9) and seismicity maps (Figure 10) in addition

to other maps to study and predict earthquakes. Although mapping provides a

very useful way of presenting information when compared with tables and

texts, sometimes they would lack the meaningfulness without referring to the

tables and texts instantly. It was not possible, before the introduction of GIS,

to visualize different maps at the same time in an efficient way. Also, maps

and attributes (e.g. the fault characteristics, ground acceleration and damage)

have to be viewed separately, perhaps in a table, which makes it more difficult

to study and predict earthquakes (Johnson).

Figure 8: This map plots the Mercalli Intensity ratings of localities near the Oct. 17, 1989 Loma Prieta (World Series) earthquake. It is called isoseismal map, as one draws contour lines to enclose locations having higher intensities; the Arabic numbers represent the local observations (S:9).

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Figure 9: Earthquake risk map. This map shows the extent of earthquake damage that is likely to occur at least once every 50 years period. Again, it can be used in planning and insurance purposes (Tarbuck).

Figure 10: Seismicity of the US (1977-1997) (S:9).

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With the use of GIS, different maps (layers), such as infrastructures

and faults maps can be viewed simultaneously as well as the attributes such

as faults characteristics and earthquakes magnitude (Figure 11).

Figure 11: A GIS view of shake map. Note how many things can represented in a single view (S:1).

In the field of seismology, GIS has been used in all three phases: 1)

management-planning, 2) mitigation-preparedness and 3) response-recovery.

Planning involves identifying the seismic hazards, risk and possible

consequences of an emergency. A process that is called Hazard Zoning, i.e.

identifying, geographically, the zones that are more susceptible to seismic

hazards on maps (Johnson).

The output of the hazard zoning process is presented in maps that are

utilized in the mitigation and preparedness activities that start after the

damage is evaluated, e.g. mapping and analyzing the relation of faults to

existing infrastructure highlights areas vulnerable to earthquakes. These

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areas, identified in the hazard zoning maps, become the focus of the

mitigation efforts, which may come in different measures such as stringent

building codes and retrofitting existing structures. Preparedness may be

achieved through several activities such as mapping evacuation routes and

public education (Johnson).

During an earthquake, quick mobilizing and targeting response effort

can help in reducing the secondary damage from fires, gas leak and water

supply contamination. Finally, recovery, in both short term and long term, can

be better coordinated through GIS by prioritizing damage repairs and careful

analysis of infrastructure and hazards before rebuilding can create more

sustainable communities (Johnson).

In addition to all of these, GIS is very important in coordinating the

efforts of participating agencies. Not only does GIS improve communication

between responders, it can help alert and inform residents of affected areas. It

gives emergency responders personnel the tools for data integration (specially

when dealing with very large data), analysis, and communication that can

make a critical difference in dealing with earthquake hazards. Even though it

is true that earthquake cannot be prevented or predicted with great certainty,

such emergency management activities, enhanced through the use of GIS,

limit the lost of life and property when earthquakes happen (Johnson).

3.2 How GIS is Used?

There are several steps toward a proper utilization of GIS in

seismology. Here, general steps will be mentioned briefly and it should be

emphasized that different steps may be applied in different circumstances

depending on the objective of the study.

The first step toward an efficient use of GIS in earthquakes assessment

is to identify the source of the problem, which is the source of the seismic

activity, mainly faults (Figure 12). After locating the source of the seismic

activity, then data collection (seismic data) is the next step. Part of the data

may be available from historic records and others have to be collected

continuously through seismographs, devices that are used to record the

seismic activity. These seismographs are linked, instantaneously, to a

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computer system using a combination of GPS, Global Positioning System,

and landlines (Gooding).

Figure 12: A GIS view of the biggest concentration of faults in the valley and mountainous region surrounding the San Andreas Fault zone and the San Jacinto fault zone (Gooding & S:1).

After managing the seismic data issue, comes the step of creating or

obtaining the maps. In general, maps are available through specialized

agencies in digital format, e.g. USGS in United States. However, one should

decides what maps should be used, which can be inferred from the objective

of the study, e.g. topographic maps, faults maps, population maps …etc. For

instant, the geographic data that comes with ArcView GIS can be used to

create base map (Gooding).

Once the data is collected and the maps are created, one should define

the parameters involved in the study (project), e.g. maximum and minimum

magnitude, and convert these parameters into the proper format (shapefile).

For instant, MS Excel may be used to create earthquake data table and then

saving the data as a dBASE file that is useable by GIS. This is the process of

creating the project database. It is of vital importance to ensure the

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consistency of the data, e.g. units of longitude and latitude. After the database

is created, table(s) may be used to create an event theme and earthquakes

may be classified by their magnitude using the graduated symbols available

through the theme legend editor (in ArcView GIS) (Gooding).

Additional steps may be added, again depending on the objective of

the study, like creating 3D, contour and triangular irregular network (TIN)

themes (Figure 13). By this, the final step has been reached, which is to

analyze and interpret the maps and the data after they have been organized

and presented in very useful and simple way (Gooding).

Figure 13: A GIS view of triangulated irregular network (TIN) created from the earthquake point theme. Faults and earthquake epicenters are visible on the surface. Areas in yellows and reds indicate shallower epicenter depths. Blue areas indicate deeper epicenters (Gooding & S:1).

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3.3 Case Studies

Three case studies are presented here: one that shows the application

of GIS in estimating the probable maximum losses after the1989 Newcastle

Earthquake, Australia. The second case shows the implementation of GIS in

the development of an earthquake risk assessment framework from the Island

of Cyprus. The last case study is from the Bay Area, CA, USA where GIS has

been used in addition to other methods in Mapping the Big One.

3.3.1 Case Study 1: 1989 Newcastle Earthquake, Australia

Even though Australia lays in a low seismic zone, in 1989, an earth-

quake of magnitude of 5.6 caused: 12 fatalities, 160 injuries and 1,124 million

insured damage. Research to estimate Probable Maximum Losses (PML) to

the insurance industry has been conducted by Natural Hazard Research

Center (NHRC), Sydney. Over 40,000 claims where reported and GIS was

used to link each claim to Modified Mercalli (MM) map (Fig. 14). GIS was very

helpful in making it easier to better understand the spatial data, e.g. spatial

location of buildings in relation to the length of streets that cross MM

boundaries (Figure 15) (Hunter).

Figure 14: Map of claim location and MM values of the areas affected by Newcastle Earthquake (Hunter).

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Input

Output

Figure 15: Estimated MM values for an earthquake of magnitude 5.6 originated at depth of 12 km. This can be used as a base map and other details, e.g. building construction and population, may be overlaid for the purpose of assessing the seismic risk associated with areas of interest. (Hunter).

Housing Data Spatial Data Geologic Data

GeographicInformation

System

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3.3.2 Case Study 2: Island of Cyprus.

GIS was used in the Developments of Earthquake Risk Assessment

framework using computer simulation. Input Parameters included, but not

limited to, population, buildings, and hydrogeology. One important assumption

were made that past earthquakes of certain magnitude would reoccur in the

same region in a defined period of time. The adopted solutions include

strengthening of existing buildings, demolition of weak buildings, level of

aseismic measures to be taken and land use planning and relocation of

population (Figure 16) (Kythreoti et al).

Figure 16: Geology of Cyprus (top), and Intensity Map (bottom) (Kythreoti et al).

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3.3.3 Case Study 3: Mapping the Big One, Bay Area, CA, USA.

GIS has been used by ABAG, Association of Bay Area Governments,

to produce comprehensive maps of seismic hazard zones in order to identify

areas prone to ground failure and minimizing damage of earthquakes. The

program is funded by Department of Interior, USGS and National Science

Foundation. The input data include data from seismographs and GPS. The

output is presented on maps containing fault traces, shaking, dam

failure…etc. Solutions implemented include programs to strengthen housing,

land use and zoning controls, disaster response planning, infrastructure and

lifeline requirements (Figure 17) (Ward).

Figure 17: A GIS map showing the distribution of faults in the West Coast area of USA. Note the major fault, i.e. San Andreas Fault that passes through the Bay Area (S:1).

4. CONCLUSION

Emergency response related to earthquakes is one area that could

benefit greatly from a coupling of GIS and short-term earthquake prediction.

Having quick access to areas that were affected most by an event, such as

travel routes and gas lines, the effect on these infrastructures could be

significantly reduced. Another important benefit is the early-warning system,

which could provide enough time to shut down nuclear reactors and close at

risk gas lines and therefore minimize along fault potential damage. GIS could

feasibly handle this task with the proper input. GIS gives emergency

responders personnel the tools for data integration (specially when dealing

with very large data), analysis, and communication that can make a critical

difference in dealing with earthquake hazards.

It can be concluded that earthquakes problem is a multidisciplinary

problem that should be talked by: Geophysicists, Geologists, Engineers and

Planners, and Socioeconomic. Scientific understanding of earthquakes is of

great importance, and it requires a big budgetary resources. As the population

increases, expanding urban development and construction works move

toward areas susceptible to earthquakes. It’s recommended, when dealing

with seismic hazards, that GIS is used in conjunction with other techniques,

such as GPS, Remote Sensing and engineering solutions. Also, all types of

seismic data, real time and historical data, should be used in data integration

so that a comprehensive database is achieved for short-term and long-term

earthquakes monitoring and prediction systems.

With a greater understanding of the causes and effects of earthquakes,

and by increasing the awareness of earthquake hazards, all together with the

up to date state of the art technologies including, and not limited to, the

utilization of Geographic Information System, it becomes possible to reduce

damage and loss of life from this destructive phenomenon.

“Even though earthquake cannot be prevented, emergency management activities, enhanced through the use of GIS, can limit the lost of life and

property when earthquakes happen.”

REFERENCES 1. “Alta Vista Home Page”. “Earthquakes and GIS at Image Search”. <http://www.altavista.com> (6 January 2003). 2. Arnoff, Stan. Geographic Information System: A Management

Perspective Ottawa: WDL Publications, 1989. 3. Bolt, Bruce. Earthquakes. New York: W. H. Freeman and Company,

1997. 4. Gooding, Margaret. “Studying Seismic Activity Using ArcView GIS and 3D Analyst”. “ESRI Home Page” <http://www.esri.com/news/arcuser/1098/quake.html> (6 January 2003). 5. Hunter, Laraine. “GIS and Natural Hazard Loss Assessment”.

<http://divcom.otago.ac.nz/sirc/webpages/Conferences/SIRC98/98Abstracts/98Hunter/Hunter.pdf> (7 January 2003).

6. Johnson, Russ. “GIS Aids Emergency Response”. “ESRI Home Page” <http://www.esri.com/news/arcuser/0701/umbrella15.html> (6 January 2003). 7. Kythreoti, Stella, et al. “GIS and Earthquake Risk Assessment”. <http://www.shef.ac.uk/civil/research/wem/riskuncert/

projects/stella_k-pg1.html> (7 January 2003). 8. Tarbuck, Edward, and Frederick Lutgens. Earth: An Introduction to Physical Geology. New Jersey: Prentice- Hall, 1996. 9. “United States Geological Survey Home Page". Earthquake Hazards Program at “Geologic Hazards”. <http://geohazards.cr.usgs.gov/earthquake.shtml> (16 December 2002). 10. Ward, Janet. “GIS and Earthquake Risk Assessment”. American City and County March 1997: 47-54.